Spectrophotometric determination of Cd(II) and Hg(II) with 2-(2`-hydroxynaphthyl azo-)benzothiazole; Application to Environmental Samples

Cadmium and mercury have a risk of disturbing the balance in ecosystem. Cd(II) is accumulated in soil and living system organism, it is easily absorbed by plants, through their root system and by leave [1]. Acid reaction of soil increases its mobility and availability. It remains in tissues for a relatively long time and is accumulated in vital organs especially in kidney and liver [2]. Contamination of fruit by harmful metals, including Cd(II) is considerably lower than other agricultural products where Cd(II) form (1M: 2L) stable yellow colored complex with 2-hydroxy 4-n-butoxy-5-bromopropiophenone [3]. Also, the toxicity of Hg compounds has caused widespread public concern as a result of several widely publicized disasters. Beginning with the minamate, Japan incident in 1950, where people were poisoned after eating seafood containing high levels of methyl mercury (27-102 μg ml dry wt) [4-6] . Analytical methods for the determination of Hg(II) ions include flourimetry [6,7], titremetry [8], spectrophotometry [9-13] and electrochemical methods [6,14]. The spectrophotometric methods reported are mainly based on ion-association of Hg(II)-complexes using reagents such as crystal violet[9], triazenes[11], bromocresol green[12] and tetraphenyl pyridine [15]. In this work, a new reagent (HNABT) was used for the determination of trace amount of Cd(II) and Hg(II) using a simple, sensitive method by producing an intense color that measured at the optimum wavelength. Also, the present study concerns the application of the proposed method for micro determination of both Cd(II) and Hg(II) in environmental samples such as water and soil and compared statistically by using AAS method.